Code 404

Following a failed operation that results in his death, top police officer John Major is resurrected by the Metropolitan Police as an AI prototype.

During an investigation, Major makes a critical error, prompting Carver to consider reporting him. However, after learning about the potential fallout, Carver chooses to conceal the mistake.

A Major, sensing that something is amiss, chooses to monitor Kelly's activities independently after receiving a new assignment from Dennett, suspecting she may have started a new relationship.

Major faces intense pressure in a critical assignment, where failure could finally lead to their permanent shutdown.

Carver is surprised when Major announces his decision to move back in with Kelly. Meanwhile, Parfit uncovers troubling details in the AI Ethics documentation.

Carver and Kelly reveal their romantic relationship as Major's AI proves to be effective, while the team prepares to capture The Juggler.

Major, now enhanced by AI, moves forward on his own path, while Carver focuses on advancing his career and investigating a high-stakes new case. Kelly has also gone separate ways, leaving the group dynamic changed.

Carver and Major uncover new leads in the unsolved Chelsea Bridge Case, a £50 million heist that occurred two decades earlier, involving a gang that mysteriously disappeared after the crime.

DCS Dennett restarts the investigation into the unsolved Chelsea Bridge case, bringing Major together with his estranged father, Clifford, who had previously worked on the case. As Major's AI system becomes more erratic, tensions arise between Dr. Parfit and Carver regarding the best approach to solving the mystery.

Major's malfunctioning AI begins to interfere with his ability to perform his duties as a police officer, prompting Dr. Parfitt to implement a solution that ultimately reveals a disturbing insight to Dennett.

Carver investigates an unstable Major while Dennett seeks assistance from Millikan Biotech. The detective inspectors take on a witness protection case involving familiar individuals, leading Carver to uncover startling revelations and confront Major.

Carver and Kelly discover a dying Major with only three hours remaining before his AI system shuts down. Despite his condition, Major is focused on solving the Chelsea Bridge case and clearing his father's name.

Major and Carver reunite after some time apart, with underlying tensions still present between them. A brutal murder of a police officer reignites their partnership, with Carver determined to solve the case and Major making a personal commitment to self-improvement. Both men are driven to prove themselves professionally.

As a serial killer continues to evade capture, Major and Carver enlist the expertise of forensic psychologist Professor McAllister to assist with the investigation, while Parfit raises concerns about the recent updates to Major's AI system.

Major confronts a new challenge as an external force targets his AI system, while Carver investigates a serial killer who is manipulating the case in increasingly disturbing ways.

Major and Carver make progress in their investigation as a key witness offers an unexpected and significant clue.

Major testifies during the trial of Chalmers, the former police commissioner who has been a persistent adversary since Major's reanimation. Meanwhile, Carver races against the clock to solve a new clue and prevent the killer from striking again.

As tensions rise within SIU, Carver races against time to prove Major's innocence and stop the killer from carrying out a deadly final act of vengeance.